In many pipelines flowing gaseous or liquid products, it is necessary to measure the flow through the line. The measuring device must extend into the line in some form or fashion. Several types of measurements may be necessary. One measurement is the flow volume as determined by a turbine flow meter. A turbine flow meter includes laterally extending blades or vanes which are spun by the passing fluid or gas. Turbine flow meters are well known in the art. They are difficult to mount, however, and it is for this purpose that the present invention has been devised.
Another type of equipment which is sometimes required in a pipeline is a pressure sensor. The total value of the product flowing past the sensor is, in part, dependent on the temperature of the flowing material. Some pipelines thus require a thermometer.
Another apparatus which requires insertion into a high pressure pipeline is a sampler apparatus. In liquid products, there is a tendency to stratify based on the weight of the molecule. Accordingly, heavier molecules settle to the bottom of the pipeline, and lighter molecules are found at the top. If a sample is removed from the very topmost part of the pipeline, it will tend towards the lighter end of hydrocarbon products. Conversely, a sampler positioned with its inlet at the very bottom of the pipe would distort the data by yielding a sample with large or heavy molecules. This problem can be alleviated somewhat by creating turbulence upstream of the sample device, but this is not a wholly desirable approach.
When an item projects into the center of the pipe, it runs the risk of being damaged by pipeline pigs which flow through the pipe. A pipeline pig is often inserted into a pipe to clean or clear the pipe. Cleaning occurs by the scrubbing action of the pig rubbing against the wall of the pipe. Most pipelines are cleaned with pigs sized to fill the cross-sectional area of the pipe. Moreover, full-sized pigs are normally required so that the pig is pushed through the pipe by the flowing product in the pipeline.
If a meter device extends into a pipe at the center, there is a risk that the pig will break off the metering device.
Heretofore, there have been devices provided which would position probes at the center parts of a pipeline. They have encountered difficulties in mounting. As an example, where they are threaded devices, they are difficult to retract for pig passage, requiring a motorized or manually operated mechanism rotating the probe for retraction. This is difficult to achieve in a minimum amount of time, and there is a further problem of starting the threads together so that cross threading and/or galling is avoided. Even when cross threading is avoided, there is some uncertainty as to the azimuthal orientation of the device presuming that the apparatus includes a transducer which must be axial with the pipe. An axial position is extremely important in flow meters, as an example.
The present apparatus is an improvement over equipment known heretofore, and, in particular, it includes and utilizes a mechanism which quickly retracts a probe assembly. It is adapted for support of practically any kind of sensor. It will be described in conjunction with a turbine sensor well known in the art. The turbine sensor is a type of device which must be parallel with the axis of the pipe. More importantly, the present apparatus is able to function repetitively with predictable repositioning both in terms of depth of penetration into the pipe and azimuthal orientation.